One of the conventional film formation apparatuses which perform a film formation process on a substrate within a process chamber is provided with a rotatable table on which a substrate is loaded. The rotatable table is maintained in a center region and is interposed between an upper hub and a lower hub. In the film formation apparatus, when six bolts passing through holes formed in the upper hub are screwed into threaded holes formed in the lower hub via disk springs, respectively, the rotatable table is fixed.
However, such a film formation apparatus has a problem in that metal contamination due to the bolts, the disk spring, and the like may occur when etching such as cleaning is performed in a state where the rotatable table is rotated at a high speed of about 240 rpm or more while a substrate is maintained at a temperature of 600 to 700 degrees C. or higher.
Specifically, a high temperature film formation process performed at a high temperature of 600 to 700 degrees C. or higher has been used in recent years. After the high temperature film formation process is performed for a predetermined period or a predetermined number of times, the process chamber is regularly subjected to cleaning. At this moment, the cleaning is performed under a temperature slightly lowered from the film formation temperature without changing the revolutions per minute (RPM). The cleaning is performed using a corrosive gas used in etching. In such a high temperature etching process, the rotatable table made of a non-corrosive material such as quartz suffers from less contamination, whereas metal contamination can occur due to the bolts, the disk spring, and the like, which are made of metal.